1. Field of the Invention
This invention relates to an assembly block formed from a polyolefin foam. More particularly, it is a block which can be used for assembling easily and inexpensively a piece of furniture or a part of a building, such as a table, stool, chair, room partition, shelf, display, planter, gate or arch.
2. Description of the Prior Art
Japanese Laid-Open Patent Specification No. 13844/1983 (publication prior to examination) discloses a building unit which comprises a block of a polystyrene foam having a pair of opposite surfaces provided with a plurality of pins and a plurality of holes, respectively, and a plurality of additional surfaces which are not provided with any such pin or hole, but are surrounded by a reinforcing cover.
The use of a polystyrene foam, however, presents a number of problems which are due to its inherent defects. The polystyrene foam is so brittle that it is easily chipped or degressed if hit by any solid object. Therefore, protection, as by a reinforcing cover, is essentially required of any exposed surface. This protection naturally adds to the time and cost which are required for a job of assembly. As its brittleness does not permit the use of any screw, blocks of a polystyrene foam cannot be used for assembling any product having a complicated shape or structure. As a polystyrene foam does not have a satisfactorily high degree of resistance to heat or chemicals, a block formed therefrom presents a worn or corroded surface or is deformed with the lapse of time. Moreover, the distortion which develops during the molding of blocks is likely to create an undesirable clearance between the adjoining blocks which are put together, or disable the assembly of a product having a desired shape or structure.